Telephone system



APPLICATION ULEB APK. I3. i918.

J. L. MQQUARRIE.

TELEPHUNE SYSTEM.

Patented Apr. 20, 1920.

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APPLICATION HLED APHx T3, HHG.

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Patented Apr. 20, 1920.

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J. L. MCQUARRE,

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EPHGNE SYSTEMx Patented Apr. 20, 1920.

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TELEPHUNE SYSTEM.

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Patented Apr. 20, 1920.

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J. L. McQuARmE.

TELEPHONE SYSTEM.

APPUCATION FILED APR.13, ISIS. 1,337,715. Patented Apr. 20, 1920.v

/rl v /1 for: James L N? Qua/wa UNITED sTATEs PATENT oEEIoE.

JAMES L. MUQUARRIE. OF MONTCLAIR, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YOR-K.

TELEPHONE SYSTEM.

Specicatinn of Letters Patent.

Patented Apr. 20, 1.920.

Application filed Api-11x13, 1918. Serial No. 228,413.

To all 'uf/Lola i1.'- mag/ concern Be it known that 1, JAMEs L. MoQUAnRin, a citizen of the United States, residing at Montclair, in thc county of Essex, State oi2 New Jersey, have invented certain new Vand useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systems and more particularly to telephone tems employinr machine switching.

The object ci this invention is to provide means whereby automatic switches ein loycd in such systems may be controlled Ef means of currents oi' different .frequencies.

In accordance with this object one feature of the invention is the provision of means for varying the impedance of a'cxjp cuit so as to cause a current of a particu ar intensit to' iiow through the circuit at different requencies.

lx1-accordance with this object, another feature of this invention is the provision of means which is operated by the various currents to selectively control the operation of automatic switches.

Other features of the invention will ap pear from the following specification and claims.

Referring now to the drawings, Figures 1 2, 3, 4 and 5, when laced together with 1iz ig. 2 to the right of ig 1, Fig. 3 below Fig. 2, and Figs. 4 and 5 to the right of Figs. 3 and 2 respectively, forni a portion of a telephone` system embodying the features of this invention. Fig. 41 represents a calling substation and a line finder switch ;.Fig. 2 represents a district selector switch; Fig. 3 represents a trunk finder switch and a set of counting relays; Fig. 4 represents regis .ters which, through the trunk finder switch land counting relays., are instrumental in ex tending a call through the district selector switch and other switches, and Fig. 5 represents circuits which are controlled by the calling subscriber to set the registers shown in Fig. 4.

In 'a number of the drawings, sequence switches such as 200 in Fig. `2, are shown. These switches are substantialllf ofthe construction disclosed in Patent blo. 1,127,808, issued February 9, 1915 to J. N. Reynolds and C. F. Baldwin. The t pe of selector switch and trunk finder switcli shown is substantialy of the construction disclosed in Patent o. 1 177,044, issued March 28, 1916 to James L. McQuarrie.

Referring now especially to Fig. 1, we will assume a call to be initiated by the subscriber at substation 100. The action of this subscriber in removing his receiver trom its switchhook results in the operation in the well-known manner, of the line finder switch 101. As soon as the brushes 102, 103 and 101 of the line finder switch reach the terminals 105, 106 and 107 respectively of the calling line, a circuit is closed from grounded battery, throughthc lower lefthand winding of repeating coil 201 (Fi 2), winding of supervisory relay 202, rightand contact of sequence switch sp'ring 203,V conductor 204, brush 103, terminal 106, conductor 108, normlal contacts of keys ,4, 3, 2, 1 and 0 in seriesg conductor `109, loop at sub station 100, .conductor 110, normal contacts of keys 5, 6, V7 8 a in series, conductor 111, terminal 107,' brush 104, conductor 205, upper contact of sequence switch spring 206, upper left-hand winding of 'repeating coil 201 to ground. Supervisory relay 202 becomes energized and closes a circuit from grounded battery, through the armature and contact of relay 202, conductor 207, brush 102, terminal 105, winding of relay 112 `to ground. Relay 112 becomes energized and stops, in the well-known manner, further movement of the line vfinder switch 101. A circuit is also closed in parallel with relay 112 throu h the Winding of relay 208 `to ground; .elay 208 becomes energized @nd closes a circuit from grounded battery, through the power magnet of sequence switch 200, upper left-hand'contact of sequence switch spring 209, righthand armature and front contact of rela 208 to ground for moving the sequence switch 200 out of position 1 and into osition 2. Relay 208 also completes a locliing circuit for itself and for relay 112 by closin a circuit from grounded battery, contact o sequence switch spring 211, left-hand armature and front contact of relay 208 to ground through the windings of relays 208 and 112 in parallel.

When the sequence switch 200 reaches position 2, a. circuit is completed from grounded battery, through the power magnet of sequence switch 300 (Fig. 3), upper right hand contact of sequence switch s ring 301, conductor 302, lower contact o sequence N :Ir

. 312,v term" 317,'conductor 324, l tirol switch 4' 210 to round, for moving the, sequences? 1lvriigtch 800gout; of position 11 and` into position 2.

In position 2 of the sequence switch 800,; a circuit is completed from rounded batl tcry,'throuh the winding o the updrivet magnet 80 spring 304, right,hand armature and back contact of relay 805, to ground. Magnetz. 3,808, upon attracting its amature, forces the driving ribbon 806 of the cord finder switch a a' t the constantly .rotat' ,roller 307 w'iio The brushes 309, sie, an, 312 and 31a move over an make contact with the associated termina 314, 815 816, 317 and 318 respectively,4 When the hrush 309 engages the terminal '314 connected to the trlmk circuit associated with the line finder 101', a circ is closed from grounded battery, throu i of relay 805, left-hand conta of sequence switchspring 319, brush 309 r- ,mmol `314 condggr, 320, 'upper left-hand .contact of soqu'" switch sprin 210 to n round. Relay .305., hecomes energized and osea l, locking fiaircuitl for v itself from grounddfa y ,through the winding ol" .relay 305; hand contact `of se uence springf319, left-hand armat of'relayl305, brush 310 coiductor 321,4pper ri ina sbt-.han conslallenc? wltch 527513.51210 t if lmv y 305 by attract' .i its rightarmature opensat Y'its y ack contact :th energizing circuit of the updrive ma et Y `to stop further upward movement o the carriage 308 and closes at its front f ntact'n circuit from grounded battery, h2 power magnet of sequence switch gend; wel' left-hand contact of sequence "spring 801., right-hand armature and front istintact' of relay 305 to ground, for moving the sequence switch 3 `tion 2 and'into position 3.

00 out of posis soon as the sequence switch 300 reaches c f2 Aa circuit is completed from e of battery, uprer secondaiy transformer 501, ower secon v i t o of transformer 501', V,(1 'Y `li), so riryhthand vinding of relay 502, ce? uctor ,upper contact of, uence switch spring hand contact of 'sequence switch spring over the lineu circuit previously dehed to the lower contact lof uence 'tch spl-inf; 206, then through con uctor 3.25, termina 818, brush 313, ugJper contact of'sequcnce switch spring 32 conductor 504, lefthadmindng of relay 502, conductorV 606, to negative pole' of battery. Relay, 502 energiaesa'nd closes a circuit for rela a .507 from grounded `battery, through wimf-y' of relay 507, armature andi'ront contact t, relay 502, te meet` by atiautractin its letand armature opens the contact of sequence switch y the brush carriage 30 -ir elevated. Y

naamw circuit of release relay $26 and thereby prevent thisrelay from eneziiz quand causing the trunk iinder swi t0 restored upon the'sequence witch 300 arriving in position 8.

Five sources of alternating current f, f, a, f and 5 each being of the same otential ut of a iii'erent frequency, are in actively connected to the twol secondary windings of the transformer 501. In accordance with the well-known laws of induction each one of these sources of current will induce an electromotive force of theA same frequency in each of the secondary `wi-ndin s of the transformer.v The secondary win" gs are 1, ade substantially the same and therefore e electromotive forces induced in each 'inding are the same. In the above traced dircuit, the' secondary windings are con- 4neet/esl together diiierentiall and as a result of this fact the elcctromoti le forces induced in one' of the windings exactly neutralize,the corresponding electromotive forces induced in the other of said windings, so that no altenatin current liows .at this time in such circ t. j

Thecircuits are now in condition for thecalling subscriber to start operating his call transmitten The A preferred form of call transmitter is shown invFig. 1 which consists of a set often keys situate at the callin substation. 'The conductors 111 and o one side of the line circutace con nected toether by two `parallel aths, one throught e normal contacts of ve of the' keys m series, such as keys 5- to 9, inclusive, and the other through the inductance 12,8. The conductors 1.08 and 109 of the other side of the line circuit are also-connected tother by' two arallel aths, one through e normal con acts 'of he other Eve keys in series such as keyls 0 to 4, inclusive, and the other through t e'nductance 124. An .inductance 113 and a capacity 114 are connected to two keys such as keys4 and 9..A A 110 dierent .inductanoe 115 and a diiferent caparity 11e are connected te two other keys such as keys 8 and 8. Similarly, di'erent inductances 117, 119 and 121 an capacities 118, 120and 122 are connected to keys 2 and 7, keys 1 and 6, and keys' 0 and 5, respecico The alternate contacts of kelys 5 to Signclusive, are connected in pai-al el to the nductor 108 so that whenever any one of these key i operated the inductance and cupac ity connected to the operated key is conneted to the conductor 108. A t the.same t1 e the normal circuit over the calling line is interrupted and two other circuits 'are closed. One 'of these circuits extends from ground, through the louve! secondary winding of the transformer 501, conductor 505, thence in parallel `through rlay 508 and condenser `513 in series, ,relay 509 and cendenser 514 in series, relay itil and condenser 515 in series, relay1 511 and condenser t in series, relay r'il and condenser il? in series, and the right-hand windingr ot relai.1 502 to 5 the Common conductor SH3, then through the upper Contact of sequence switch spring brush 32, terminal 23.17, conductor 32d, lefthand contact off sequence witch spring' 2G23, Conductor 2li/lij brush lflll, terminal 10G, conm doctor 108, to ground through the alternate contact of the depressed key and the par-- tisular induetance and capacitr connected thereto. The other circuit may he traced l from ground, through the upper secondary 1h' Winding of the transformer 50i, battery7 thence in parallel to the conunon conductor 504 through relay 518 and rondenser 523 in series, relay 519 and cond@ awr 524 relzqP 520 and condenser 525, rela)v hdl and condenser 526, relay and condenser 52'?, and left-hand winding of relay then through the upper Contact of sequence switch spring 323, brush 31:, terminal 31S, conductor 325, lower Contact of sequence switch spring 206,

conductor 205, brush 104, 'terminal lll?, corr ductor'lll, inductance 123, loop at sah-stas tion 100, conductor 109, normal contacts of keys 0 to 4 inclusive to ground through the alternate Contact of the depressed key and the particular inductanee and capacity connected thereto.

The relays 508 to 512 inclusive, and relays 518 to 52:2 inclusive are alternating current relays, each of which will not operate until a particular value of alternating current of a particular frequency Hows through its winding. di current of a different frequency is required to operate each one of the relays 508 to inclusive and similarly, a current 40. of different frei'lneucy is required to operate each one of the relays 5113 to inclusive.

Each of the sources of current f1 to f5 induces an electromotive torce of a corresponding frequf'fucy in earl] of the drscrihed circuits, and cach of those induced electrometire forces causes a current of a corresponding frequency to low through each of these circuits. The capacity and inductance of the first mentioned circuit are of such values that resonance occurs for one of the electrow motive forces induced therein, thereby cans ing suificient current of the corresponding frequency to ilow through this circuit to cause the particular one oi' the relays 508l to 512 incluswe to operate, l'which operates at such frequency. the capacity and inductance of the first mentioned circuit are, howlever, of such values that theyT 'prevent soilicient current, produced hy any of the other 60 inducted eleetromotive forros, from flowing through the circuit and operating' any other one ol the relays S to 512 inclusive. The particular oneo the relays 50S to l inu elusive which operates, controla a register in a manner hereinafter descrilled.

The capacity and inductance of the second uhm e traced circuit are of such values that none of the eleetreinnotive forces induced in the upper secondary windingl of the transformer 50i produce suilicient current in this circuit to operate any of the relays to 5552 inclusive it xviii? ih rurssir?, a pfiitieuiar ow oi the hcys .tios o to il ,inc usire, elertrolnotivc forces of diller` ent frequencies are induced in two diifrrent circuits, eac-lx oi which includes one side of the line' connectiner the calling substation to the central oilice. YThe impedance oi one of these circuits is so desi Y[red that resonance 1a/:ruis for one ot' the cleotrennotive forces iduoed therein, which is oi' a particular ireoueuoy, and as :L result olf this` soliriout rol rent llows at this1 particular i'rcquency'to operate a particular alternating;y current relay which Controls the setting of the registers. This impedance, however, is such that it prevents sulieient current of any other i'ri'efnienries from flowingy through t|ii cir- Cuit to operate any one of the other alternating current relays. rThe impedance'of the other circuit closed hy the depression of such key, is such as to prevent sufficient current of any frequency to flow through such circuit to operate any one of the alternating; current relays therein.

By depressing any other one of the keys Nos. 5 to 9 inclusive, a different indnrtauce and capacity is included in the ahore trai-.od circuits.

The impedance of the first traced circuit will be changed nach time a different key is depressed so that resonance will occur for a diil'erent one of the electromotire forces induced in the lower secondary winding ol' the transformer 501. Sulicient current or the corresjionding frequency then lown through this circuit and operates the particular one of the relays 50S to Irl?. inclusive, which operates at such frequency As he fore the new impedance of this circuit and the impedance of the second traced. circuit.

which is also changed each time a different key is depressed, arene designed that none of the other nine'alternating 'current relays operate.

It lwill, therefore, he observed that the depression of a particular one of the keys Noe. 5 to 9 inclusive will cause a particular one of the relays 518 to 522 to operate.

The alternate contacts of keys Nos. 0 to 4 inclusive, are connected in parallel to the conductor 1]() so that Whenever any one of these keys is operated such contact is connected to the conductor 110. At the saine time the circuit th rough the normal contacts of keys Nos. (l to Il; inclusive. is opened and thereby' the normally closed shunt circuit aroun the inductance 194 is broken.

The normal circuit over the culling; line riore, he ohserved that il; de@

is thereby interrupted and two other circuits are closed. One of these circuits extends from ground, through the lower secondary winding of the transformer 501, conductor 505, thence in parallel to the common conductor 503, through relay 508 and condenser 513 in series, relay 509 and condenser 514 in series relay 510 and condenser 515 in series, relay 511 and condenser 516 in series relay 512 and condenser 517 in series, and the right-hand winding of relay 502, then through the upper contact of sequence switch spring 322, brush 312, terminal 317, conductor 324, left-hand contact of sequence switch spring 203, conductor 204, brush 103, terminal 106, conductor 108, inductance 124, conductor 109, loop at substation 100, conductor 110, to crround through the alternate contact of the depressed key and the particular inductance and capacity connected there to. The other circuit maybe traced from ground, through the upper secondary winding of the transformer 501, battery, conductor 506, thence in parallel to the common conductor 504, through relay 5l8 and condenser 523 in series, relay 519 and condenser 524 in series, relay 520 and condenser 525 in series, relay 521 and condenser 526 in series, relay 522 and condenser 527 in series, and left-hand winding of relay 502, then through the upper contact of sequence switch 323, brush 313, terminal 318, conductor 325, lower contact of se uence switch spring 206, conductor 205, brus 104, terminal 107, conductor 111, normal contacts of keys Nos. 5 to 9 inclusive, conductor 110 to ground through the alternate contact ot the depressed key and the induetance and ca acity connected thereto. ach of the sources of current f1 to f5 inclusive, induces an electromotive force of a corresponding fre uency in each of these circuits, and each oil these induced electromotive forces causes a current of a correspending frequency to llow through each circuit as above described.

The impedance of the first traced circuit is so designed, however, that none of the currents therein operates an one of the relays 508 to 512 inclusive. he impedance o the second traced circuit is such, however, as to produce resonance for one of the electromotive forces induced therein, and as result suiiicient current of the proper freuencylows through this circuit to operate t e particular one of the relays 518 to 522 which is operated by current vof such frequency. This impedance of the second traced circuit is of such a value, however,

as to prevent suiiicient current of any other frequency from fiowing to operate any other one of the relays 518 to 522 inclusive.

By depressing any other one of the keys Nos. 0 to 4 inclusive, a different inductance and capacity is included ineagch of the above i right-hand contact of sequence Switchs .re ay 528 to traced circuits. The impedance of the last traced circuit is changed each time a diferent key is depressed so as to produce rescnance for a dierent one of the electroxnotive forces induced in the upper winding of the transformer 501. Sufficient current of the corresponding frequency then iiows through this circuit and operates the particular one Y of the relays 518 to 522 inclusive, which operates at such frequency. As before, the `v new impedance of this circuit and the impedance of the first traced circuit, which is changed each time adifl'erent one of keys Nos. 0 to 4 inclusive is depressed, are so designed that none of the other nine alternatso ing current relays operate.

Iherefcre, it will be observed that the depression of any one of the keys Nos. 0 to 9 inclusive will operate acertain one of the rela s 508 to 512 inclusive or a cer- 35 tain one the relays 518 to 522 inclusive. It should also be observed that each time any one of they keys is depressed, there is always a circuit completed through battery for the winding of the relay 502, and therefore this relay remains energized.

For this description it will be assumed that when key No. 0 is depressed, relay 522 is operated, when key No. 1 is depressed, relay 521 is operated and in a similar manner when the keys Nos. 2 to 9 inclusive are depressed successively relays 520, 519, 518, 512, 511, 510, 509 and 50S respectively are operated. v

We will also assume that .the number corresponding to the tele hone of the party Wanted is 05944, the igit 0 representing the oiiice in which the wanted partys linel terminates. The calling subscriber thereupon presses keys Nos. 0, 5, 9, 4 and 4 in succession.

In response to the depression of key No. 0, suiiicient current of the pro er frequency flows through the Winding o relay 522 to cause it to attract its armature and complete a circuit from grounded battery, through winding `of relay 528, armature and front contact of relay 522, conductor 529, upper rin 530, winding of relay 531 to ground. ela 531 becomes energized and closes a locking circuit for itself from grounded battery throughontactof sequence switch' spring 327, conductors 3284 and 532, left-hand' ary mature and contact of ofV relay 531 to ground.

Relay 528 also is energized in the above traced energizing circuit of relay 531 and closes s, circuitv from grounded battery, through winding of the slow-to-rclcas'e rela 533, armature and front contact of ground. As soon as the key No. 0 is released the relay 522dener s and opens the circuit of rela '523W clay 528 denergizes and closes agiollowing 13,0

relay 531, winding ;I

las,

. is then established The setting of the thousands register the hundreds register, the tens register, and the units register is similar to that described in connection with the setting of the odios reister, and these settings take place inn taneousl When all are completed the re isters w'- l be in the following ositions: t e oice register' in position 0, t e thousands register in'position 5, the hundreds register in position 9, the tens register in position 4 anA the units register in position 4.

t this time also the shunt around the windin of relay 458 is removed and there fore su `cient current will flow throu h its winding to cause its energization. A circuit from grounded battery, through the power magnet of sequence switch 300, right-hand contact of sequence' switch spring 329, conductor 330, amature and contact of relay 458 to ground for moving the sequence switch 300` out of position 3 and intoy ition 4.

When t e sequence switch 300 leaves position 3 the holding circuits of rela 531, 536, 540, 544 and 546 are opened. hese relays denergize and open the circuit of rela s 450, 451, 452, 453 and 454 respective y. Each of these last mentioned relays retracts its armatures and in so doing causes the deenergization of both relays 556 and 458.

Relay 556, in retracting its amature, closes a circuit from grounded battery, through the power magnet of sequence switch 300, left-hand contact of sequence switch spring 329, conductor 331, armature and back contact of rela 556 to ground, for moving the sequence swltch 300 out of position 4 and into position 5.

While the sequence switch 300 was in position 4 a circuit was completed from grounde battery, through the power magnet of sequence switch 200 lower contact of sequence switch spring 209, conductor 332, terminal 316, brush 311, contact of sequence switch sprin 333 to ground, for moving the sequence switch 200 out of position 2 and into position 3.

lVhen seguence switch 300- reaches ition 5, the undamentalcircuit is comp eted and extends from grounded battery, through winding of relay 212, uppe:` contact of sequence switch spring 213, conductors 214 :und 325, terminal 318, brush 313, lower contact of sequence switch spring 323, youter armature and back contact of relay O, winding of stepping relay 334, lower contact of sequence switch spring 322, to ground.V

Relay 212 becomes energized and establishes through its right-hand armature and front contact and the lower left-hand contact of sequence switch spring 213, a locking circuit forf itself to ground over the above traced circuit. Relay 212 also closes a circuit froln v,f rrmuulml battery. through the power magnet of sequence switch 200, upper `posmtion 4. f

hand armature` and front Ying roller 219, whereb 'f contact of relay 334 to ground. Counting 90 r In position 4 of sequence switch 200, a circuit 4is closed from grounded battery, through the winding of upldrive magnet 216, contact of sequence switc spring 217, leftcontact of relay 212 to ground. Magnet 216 attracts its armature and in so doing, p the driving ribbon 218 against the constantly rotatthe brushA carrie 220 is elevated. As t e brush 221 p w.: over the commutator 222 the stepping relay 334 is intermittently denergize an gized as hereinafter described.

Upon the initial energization of relay 334, grounded battery,

a circuit is closed from through winding of counting relay O,l conductor 335, lower contact of spring 403, conductor 336,upper letand contact of sequence switch spring 337, amature and relay 0 is thereupon enerized and closes a circuit from grounded atte throu h windings of counting relays and armature andY contact of'cuntin relay O, right-hand contact of sequence switch spring 328 to ground. Countlng4 relay 0', however, is shunted through the conductor 335 over the circuit previously described, and therefore does not energize until relay: 334 denergizes.

When the commutator brush 221 asses over the first conducting'segment o commutator 222, a shunt circuit is closed around the winding of relav 334 ed battery, throng the winding of relay 212, right-hand armature and contact of relay 212, lower right-hand contact of saquence switch sprin 213, conductor 223,

lay 334 thereupon denergizes and this reground for moving the seas follows: groundsults` in the energization of countin relay Of. Counting relay O', by attractlng its outer leftl "'nd armature, opens the fundamental-ef uit, and removes the ground at the lower 4left-hand contact of sequence switch Y ring 322 from the circuit leading to relaygg Therefore as soon as the brus 221 reaches an insulating segment of the.

comlmitator 222,7the relay 212 becomes deenetgined. As the relay 212 denergizes it opens the circuit of the updrive m net 216, whereupon the brushes 224. 225 an 226 seL cured to theY brush carriage 220 come to rest 4 at the bottom of the selected group of trunks.

The dcnergization of relay 212 also closes a circuit from grounded battery, through power magnet of sequence switch 200, upper left-hand contact of sequence switch-.spun 215. left-hand armature and back contact o relay 212 to ground, for moving the Sequence switch 00 out of position fi amil inw pour -tion 5.

220 has, hren (lrwuwl. through luuslr umm ture und bruik nntcf uf comming; relay conductor 339, uppor loft-wml contact nl? n pout-ifm i) of thu saquear@ Swf'lx. 300, Hw fuuflzuueuul uil-ruil., is lm cluswl lfmuglr in the wen-md .Salad-Luz zwtarh mul gmup svlctiou thaw-.1t will new: mlm place. As thu Swtf'h shaft is elevated. current through the relay 334 will he interrupted by mmm wf u shunt circuit in the wellluowll manncr. Upon the initial errf-,rgiznifm of relaja 334, a circuit is Closed from grounded lmtafry. wimling; n? taunting relay 13. rmalure und 3mdk Contact 0l counting relay 3. Gumuotors 341 and 460. upper cli-rituel; mi' :sw queme swirll spring 453.1, upper Contact of? Hmmm-,n switll spring 412, conductor lower rghbhzmd Contact of sequence switch sprug 337, ammi-,ure and mntact of may 334 to gruund.` Each subsequent denergization and energization of i'elay 334 actuates the counting relays in the well-known manner. As soon as the counting relay O cnergizes, it opens the fundamental circuit, thus ending the second cycleof operations and stopping the thi d set o f brushes at the second selector switc at the bottom of the fourth group of trunk terminals. The brushes of the selected set will now be caused to hunt f terminals associated with an idle iinal select switch.

The energization 4 of countin relay O also closes a circuit from bun ed battery, through power magneto sequence switch 300, inner armature and contact of counting relay O', left-hand' contact of sequence switch spring 338 to ground, for moving the sequence switch out of osition 9 and into position 11. Th'e holdlng circuit for the counting relays is interrupted at the righthand contact of sequence switch spring 338 as before. 4

As soon as the second selector finds an idle trunk, the fundamental circuit is closed to the final selector switch associated with such idle trunk. Brush selection at the final selector switch will now take place. As the inal selector switch shaft is elevated, current through 334 will be interrupted by means of a shunt circuit in the well-known manner. Upon the initial energization of relay 334, a circuit is closed from grounded battery, through winding of counting relay 4, armature and back contact of counting relay 4', conductors 343 and 461, right-hand contact of register spring 422, conductor 344, lower left-hand contact of sequence switch spring 337, armature and contact of relay 334 to ground. Each subsequent deenergization and energiaation of relay 334 actuates the counting relays in the wellknown manner.

As soon as the counting relay O becomes energized, the fundamental circuit is inter-` rupted, thus te inating the brush selection at the linaiglector svitch. The energlzation of counting relay O also completes a circuit from grounded battery, through power magnet of sequence switch 300, inner armature and contact of counting relay 0', left-hand contact of sequence switch spring 338 to ground, for moving the sequence switch out of position 11 and' into position 13. When the sequence switch loaves position l1, the holding circuit for the counting relays is opened as before.

When the sequence switch 300 reaches position 13, the fundamental circuit is again closed through to the final selector switch. Tous selection thereat now takes place.

Upon the encrgization of relay 334 when the fundamental circuit is closed, a circuit is completed from grounded battery, through counting relay 4, armature and back contact of counting relay 4', eenductors 343 and 462, lower right-hand con tact of re ister spring 431, conductor 345, right-ham? contact of sequence switch spring 346, armature and contact of relay 334 to ground. The. counting relaysare then actuated in the well-known manner.

As soon as counting relay 0 is energized, the fundamental circuit is opened, thus selecting the tens group of terminals in which the called subscriber s line terminals are located. The energization of counting rrelay O' also completes a circuit from grounded battery through the power magnet of sequence switch 300, inner armature and con- 'ta'ct of counting relay O', left-hand contact of sequence switch spring 338 to ground, for moving the sequence switch out of position 13, and into position 15. The holding circuit of the counting relays is open at the right-hand contact of sequence switch spring 338 when the sequence switch 300 leaves position 13.

When the s uence switch 300 reaches position 15, the undamental circuit is a ain closed, and units selection now takes p ace.

Upon the ener ization of relay 334 by the closing of the undamental circuit, a circuit is closed from grounded battery, through counting relay 4, armature and back contact of counting relay 4', conductors 343 and 463, lower right-hand contact of sequence switch spring 441, conductor 347, left-hand contact of sequence switch spring 346, armature and. contact of relay 334 to ground. The counting relays will be energized inthe well-known manner until the countin relay O is energized. Counting relay 0 interrupts the fundamental circuit, thus determining the terminals on which the brushes of the final selector switch shall rest. The energization of counting relay 0 also closes a circuit from grounded battery, through power magnet o sequence switch 300, inner amature and contact 'of counting relay O', left-hand contact of sequence switch spring 338 to ground, for moving the sequence switch out of position 15 and into position 16.

In position 16 of sequence switch 300, a circuit is completed from grounded battery, through power magnet of sequence switch 200, lower contact of sequence switch spring.;r 209, conductor 332, terminal 316, brush 311, contact of sequence switch spring 333 to ground, for moving the sequence switch 200 out of position 11 and into position 16.

Sequence switch 200 in moving out ofposition 11, opens'at the upper right-hand contact of sequence switch spring 210, the holding circuit of relay 305. Rela 305 is thereupon denergized, and comp etes a circuit from grounded battery, through power magnet of sequence switch 300, lower right-hand contact of sequence switch spring 301, rightsoA mamas iialbe; will (Uhr piave :w foinws: when the Ki pmw hir; receiver upon :ii-hand@ Hifi irl-uit nf relay 502 will ML Nimah! im reim-hw swih'h 3U() wil! he iii piisiiwsa :mii swqiiiu'v Switch 2U() in poitiiix-r. 2 :n this time)A The cnntiimvi? de.m imagination of rvhrv .302 causes the df'mra ,fixation of i'ohiy :'ili, ifiruilit is than rhsfisfx '5mm grounded battery. through pow-r unigeniuf sfwpwurei .fiwitrh MU, ujii mrt of saquen@ switrh Spring 548.1 right- ]mmi armature :mel rmitrut 0f rola); 5U?, urlim'iise anni hugh. militari uf reiay 502 to gfrmmf' fiar mining' Uw swplauru switch 500 inw its nir-mm1 poitinn. The .hrmrgzw tion, Qi' relay 50T also rimes n rirrnit. from rounded hatte-1W tiarfmgfh winding u!" rcay izirt of wquefmr Sivitvi's wiring 25523, .-uuiurm- 354, left-hand nrmiiturv nml hawk rmlzlr iai' rchiy 5H? in ggrnmu. hlfi zii hvwmus vnvrgizcii :mii riosrs i1 lurking rirv-sii [ur tsfef frifui grounded hai-wry, hriiiifh minding uf rviay 3726, righfhnm :i :aww terni unitari if rolziy 326, coni-mt pf sffiiwsiii'v swirh L\pri1i`;' 355 to ground.

pmwr magnet of Sequence switch 300, mn- 'nw( of Hveplesiru swim-h spring Sf loft'- mm? armature and mutzirt of rilzly 326 to ground, for mnviiig' the Soquence switch 300 rmt of position 3 und intn position [6.

L Ir. :i tillephmu; i'i:riy1. :1 rin-uit, vari :lhiy upm-ahi@ ziilhmmrii' rnrii'rhm :1 piilrzii ity ni' smis'mlsx ni' Miri-mi ronnuflterl to said ('iri'nitn rauh hving of :1 iliifcrvnt freqnemy, rrrt'maingxwir ih'viwfs iarhii'ied in suiri 'iruit fur rmxtrnling the wsrfxhie operation mi said win-huez. :mei moslim i'nr placing mici f-iriuit in mmhtmi of rwsuimnvv for Puch um of, Said simrrvs :if lirurrfnt to Selm'tively wpvrutu Suid denti-011mgnutic svces.

2. In :a tvlvphonc system. fariahly (ipernhh nilunmtir swirl-hens. :i rrcuit, n ph1ra|- iig; ui" sneirrvs, nf alternating (1n-rent rmiuritm iwi'ftm menus for viigying the im pwhmr nf said rircnit to Yury the mirrvnts prmhiriw in smid vii-ruit, by Said Soin-CUS n? mia'rmit imi] mvims svierively operated hy .anni i'airinus riirrvnts fm' f'mitrulling tlif mriuhlu npei'aition uf said switvhes.

3. In a telephone system, a pair of conductors, a plurality of sources of alternating current connected to each conductor, electromagnetic devices connected to each of said conductors, a plurality' of different impedances, and means for closing a circuit throu h either of said conductors and any one o a plurality ot' different iinpedances to place such circuit` in condition of resonance for one of said sources of current to selectively operate said electromagnetic devices. y

4. In a telephone system, automatic switches, a pair of conductors, a 4plurality of sources of alternating current connected to each conductor, electromagnetic devices connected to each of said conductors for controllingthe operation of said switches, a

l plurality of different impedances, and means for closing a circuit through either ofsaid conductors and any one of a plurality of different impedances to place said circuit in condition of resonance for one of said sources of current to selectively operate said electromagnetic devices.

lin a telephone system', a pair of conductors, af plurality of sources of current connected to each conductor, electromagnetic devices connected to each of said conductors, a plurality of different impedances. means for closing a circuit including said conductors in series. said electromagnetic devices being non-responsive to` the current in said circuit, and means for closing a circuit through either of said conductors and any one of said impedances to place such last mentioned circuit in condition of resonance for one of said sources of current to selectively operate said electromagnetic devices.

6. In a telephone system. automatic switches. a plurality of conductors, a plurality of shurces of current connected to cach conductor, electromagnetic devices connected to cach of said conductors for controlling the operation otisaid switches. a plurality of dili'erent impedances,4 means for closing a circuit including said conductors in series, said electromagnetic devices being non-responsive to the current in said circuit, and means for closing a circuit through either of said'conductors and any one of said impedances'to place such Vlast mentioned circuit in condition of resonance for one of said sources of current to selectively operate said electromagnetic devices,

7. In a telephone system. a pair of conductors. a. plurality of' sources of current connected to each conductor, electromagnetic devices connected to each of said conductors, means for closing a circuit through either of said conductors, and means in said circuit for placing said circuit in condition of resonance for one of said sources ot current to selectively operate the electroniagrn netic devices connected to the conductor tlirou l1 which the circuit is closed.

8. n a telephone system. a tclcplmne line. automatic switches. a plurality of sources of current, each ot' a different frequency, means for connecting said sources of current to said line, and means lor closing through said line resonating: circuits for `each one of said sources of current to -selectively control the operation of said switches.

9. ln a telephone system, a telephone line. automatic switches. a plurality ot' sources of current, cach of said sources of current being of a different frequency. means for connectingr said sources ot' current to said line, means for closing through said line resonating circuits for each of said sources of current, and means selectively operated by the current' in said resonatingr circuits for controlling' the operation of said switches.

'10. ln a telephone system. a subscribers line, automatic switches. a plurality ol -sonrces of current. each of said srulrccs of current being of a different freiniency, means for connectingr said sources of cur rent to said line, means under the control of said subscriber for closing resonatingr circuits through said line for each of said sources of current. and means selectively operated by the current in said` rcsonating circuits for controlling` the operation oi" said switches.

In Witness whereof l hereunto subscribe my name this 6th day of April. D. l9l.'

JAMES L. licQVARRlE. 

